Fortress (Bone 2) ready to ship formicarium What does add a second

What does add a second side mean

See photos accompanying this product for more recent versions

The Mini Hearth is a starter/founding formicarium created by Tar Heel Ants

6" diameter

Fortress (Bone 2) ready to ship formicarium What does add a secondThis product is available for immediate shipping and ships within 2 3 business days after ordered. See this fortress link for more information about this formicarium. Features: Bone Exterior, Grey interior Type I material (AAC aka "Ytong") Medium Large sized tunnels and chambers Rocky Woodland Foraging Decor Museum Glass Optional 95% glare reduction (Shown in photo) Removable Vent optional What comes in the box? Fortress formicarium (as seen in